What are the lymph nodes?
The lymph nodes are pinhead- to bean-sized organs located mainly in the neck, armpits, groin, chest and abdominal cavity. Linked by the lymphatic vessels, they form a net throughout the body. They filter microbes, cancerous cells and foreign particles from the body fluid called lymph and are therefore a part of the body’s immune system.
Shape and Size
The lymph nodes appear as small balls that have a bean-like shape. Normal nodes around the ears, on the inner sides of the elbows and behind the knees can be as small as few millimeters, while those in the groin can reach 1.5 centimeters [4]. In some healthy older children, the lymph nodes in the neck and armpits can be palpated, while in healthy adults, except in some very skinny ones, they usually can not be [3]. Normal lymph nodes are usually not visible.
Swollen lymph nodes can range from about 1 to more than 5 cm [4]. Swollen nodes in the neck, around the ears, at the back of the head, in the armpits and groin can be visible and palpated. When palpated, they appear as soft or firm lumps with well-defined borders.
Lymph nodes can become swollen (enlarged) due to infections, insect and snake bites, autoimmune disorders, cancers, long-term exposure to silicon or beryllium and genetic storage diseases [1,4].
Structure
The lymph node has the pulp-like center covered by the capsule.
The capsule is composed of dense connective tissue. A quick expansion of the lymph node, for example, during an acute infection, results in a capsule stretch, which causes pain.
The cortex houses the lymphoid follicles, which contain mainly B lymphocytes [14].
The paracortex contains mainly T lymphocytes.
The medulla contains mainly macrophages (which ingest foreign particles) and plasma cells (which are derived from B lymphocytes and produce antibodies, which are spread via the blood and fight microbes all over the body).
The lymph is composed of the fluid that is derived from the blood plasma–it appears around the cells (interstitial fluid)–and from the lymphocytes. The lymph is delivered to the lymph nodes via the lymphatic vessels.
The afferent lymphatic vessels drain the lymph from a certain area, for example, the afferent vessels of the submandibular nodes drain the lymph from the mouth and the facial skin.
Within the lymph node, the lymph flows through the system of sinuses and present microbes and other foreign particles to the lymphocytes.
The efferent lymphatic vessels collect the lymph from the lymph nodes and deliver it to the subsequent nodes. For example, the efferent vessels from the popliteal nodes behind the knee deliver the lymph to the inguinal nodes in the groin. Eventually, all the lymph drains into the subclavian veins, either directly, but mostly via the right lymphatic or left lymphatic (thoracic) duct in the chest cavity and via the jugular trunk in the neck.
The lymph nodes have their own arteries, which deliver the blood with the nutrients and lymphocytes to them [14,22]. The blood leaves the lymph nodes via the veins.
Function
The lymph nodes filter the lymph: they remove and destroy bacteria, viruses, parasites, fungi, cancer cells and foreign particles from it [14].
The roles of different cells in the lymph nodes:
- B lymphocytes produce antibodies.
- T lymphocytes directly destroy microbes and foreign particles.
- Macrophages ingest microbes and foreign particles and present them to the lymphocytes.
The lymph nodes filter the lymph in a similar way in which the spleen filters the blood. The lymph nodes do not remove toxins and drugs from the body as the liver and kidneys do. The lymph nodes are the only organs that filter the lymph.
Together with the spleen, bone marrow, tonsils, thymus, the lymphatic tissue in the small intestine and white blood cells (leukocytes), the lymph nodes form the human’s immune system, which fights against infections.
Locations
There are hundreds of lymph nodes in the human body. They appear in groups, mainly in the neck, under the jaw, around the ears, at the back of the head, in the armpits, groin, chest and abdominal cavity and on the inner sides of the elbows and knees.
Chart 1. Lymph Node Locations |
|
| HEAD | Preauricular and parotid, Retroauricular, Occipital, Submental, Submandibular |
| NECK | Anterior superficial, Posterior superficial, Anterior deep, Superior deep, Inferior deep |
| ARMPITS | Axillary |
| ARMS (elbows) | Supratrochlear |
| CHEST | Bronchopulmonary, Mediastinal, Hilar |
| ABDOMEN | Iliac, Lumbar, Sacral, Retroperitoneal, Mesenteric |
| GROIN | Inguinal, Femoral |
| LEGS (knees) | Popliteal |
Head
Preauricular and Parotid Nodes
Location:
- Preauricular nodes: in front of the auricle at the level of the tragus
- Parotid nodes: in front and below of the auricle, over the parotid gland
Drainage: the skin at the temples and front of the head, the front side of the ear’s auricle, external ear canal, lateral two-thirds of the eyelids and conjunctiva, the root of the nose [3,4,5,6,7,16-s.105]
Efferent lymphatic vessels lead to the anterior superficial or superior deep cervical nodes [16,17].
Retroauricular (Mastoid) Nodes
Location: behind the bottom of the auricle
Drainage: the back side of the auricle, external ear canal, skin from the temples and top of the head [6,7]
Efferent lymphatic vessels lead to the superior deep cervical nodes [1,16].
Occipital Nodes
Location: at the base of the skull, at the back of the head near the hairline
Drainage: the scalp at the back of the head [8]
Efferent lymphatic vessels lead to the superior deep cervical nodes [8].
Submental Nodes
Location: under the chin
Drainage: the tip of the tongue, the front part of the mouth floor, the front lower teeth (incisors) and the related part of the gums, the skin of the chin and the medial third of the lower lip [7,8].
Efferent vessels lead to the submandibular and deep cervical nodes [16].
Submandibular Nodes
Location: under and medially to the jawline (NOTE: medially to the submandibular nodes, there are submandibular salivary glands)
Drainage: the skin on the cheeks, sides of the nose and below the jaw, the medial third of the eyelids and eye’s conjunctiva, the front half of the nasal cavity, paranasal sinuses (maxillary, frontal and ethmoid sinuses), upper lip, lateral 2/3 of the lower lip, upper and lower teeth and gums except lower incisors, lateral parts of the front 2/3 of the tongue, sides and palate of the mouth, submandibular salivary glands and the submental nodes [1,3,6,7,8,16]
Efferent vessels lead to the superior deep cervical nodes [16].
Retropharyngeal Nodes
Retropharyngeal nodes lie between the pharynx and spine and cannot be palpated. They drain the nasal cavity, the nasal part of the pharynx and the auditory tubes [8]. The efferent vessels lead to the superior deep cervical glands [8].
Neck
Lateral Superficial Cervical Nodes
Location: over the sternocleidomastoid muscle (which extends from the mastoid process behind the ear diagonally down toward the sternum and clavicle), along the external jugular vein
Drainage:
- The skin of the neck, parotid gland [4,6,7,8,9]
- The preauricular nodes [1]
Efferent vessels lead to the deep cervical nodes [16].
Anterior Superficial Cervical Nodes
Location: on the sides of the larynx and trachea, along the anterior jugular vein
Drainage: the larynx and trachea
The efferent lymph vessels probably lead to the deep cervical nodes.
Anterior Deep Cervical Nodes
Location: in the middle of the neck, in front of the larynx and trachea [8,26]
Drainage: the larynx, trachea and thyroid
The efferent lymphatic vessels lead to the superior deep cervical nodes [8,26].
Superior Deep Cervical (Jugular) Nodes
Location: Under the upper part of the sternocleidomastoid muscle, along the internal jugular vein [19]
Drainage:
- The posterior third of the nasal cavity, paranasal sinuses, mouth, larynx (voice box), the upper parts of the trachea and esophagus, thyroid gland, parotid glands [17,19,20,21]
- The scalp at the back of the head (via occipital nodes)
- The uppermost superior deep cervical or jugulodigastric node, which lies at the side of the neck just below the jaw angle, drains the posterior 2/3 of the tongue, pharynx and soft palate including the palatine tonsils [8,21].
The efferent vessels lead to the inferior deep cervical nodes.
Inferior Deep Cervical (Jugular) Nodes
Location: behind the posterior border of the lower part of the sternocleidomastoid muscle [8].
Drainage: the larynx, thyroid, esophagus, other head and neck nodes [16,17]
Efferent vessels lead to the jugular trunk in the neck and eventually to the thoracic duct, right lymphatic duct or subclavian vein [19].
Supraclavicular Nodes
Location: above the clavicles on both sides of the neck (in the supraclavicular fossa)
Drainage [3,25]:
- Right: the mediastinum (the space between the lungs), esophagus, lungs
- Left: via the thoracic duct: the gastrointestinal and genitourinary tract
- Both: via the cervical nodes: the head and neck; via the axillary nodes: the breast; skin of the arm, chest and back
Efferent vessels lead to the jugular trunk, left (thoracic) or right lymphatic duct or subclavian vein [16].
Infraclavicular Nodes
Location: below the clavicle, between the deltoid and pectoralis major muscle.
Drainage [10,14,17]:
- The upper lateral portions of the breast
- The radial side of the arm and palm and the thumb and index finger
- Axillary (armpit) lymph nodes
Efferent vessels lead to the subclavian trunk and eventually to the subclavian vein [10].
Armpits
Axillary Nodes
Location: in the armpits
Drainage: breasts, chest, upper back and abdominal wall above the belly button, arm, hand and fingers [1,3,10,14]
Efferent vessels lead to the infraclavicular and supraclavicular nodes, the subclavian lymphatic trunk and eventually to the subclavian vein [10,25].
Arms
Supratrochlear (Epitrochlear, Cubital) Nodes
Location: on the inner ulnar (pinky) side of the elbow [10]
Drainage: the pinky, ring and middle finger and the related parts of the hand and forearm [5]
Efferent vessels lead to the axillary nodes [10].
Chest
Tracheobronchial Nodes
Location: around the division of the trachea into the bronchi [17]; and more laterally: bronchopulmonary nodes (before the lungs) and pulmonary (within the lungs) [17]
Mediastinal Nodes
Location [13]: in the chest, between the lungs
Drainage: the lungs, pleura, heart, pericardium, thymus, esophagus, trachea, bronchi [13]
Hilar Nodes
Location: at the entrance of the bronchi into the lungs (hilum)
Drainage: the lungs, pleura, heart, pericardium, thymus, esophagus, trachea, bronchi [13]
Abdomen
Locations [12]:
- External and internal iliac nodes: along the external and internal iliac arteries in the groin and pelvis
- Mesenteric nodes: between the 2 layers of the mesentery – the membrane that attaches the intestine to the abdominal wall
- Lumbar (paraaortic, periaortic) and sacral nodes: in front of the lumbar and sacral spine
- Retroperitoneal nodes: at the back of the abdominal cavity
Drainage: abdominal organs (stomach, liver, gallbladder, pancreas, kidneys, intestine) and pelvic organs (bladder, prostate, testicles, uterus, Fallopian tubes, ovaries) [12]
Efferent vessels lead to the intestinal lymph trunk, cisterna chyli, left lymphatic duct (thoracic duct) [12,23] and, possibly, to the left supraclavicular (Virchow’s) node [24].
Groin
Inguinal Nodes
Location:
- Superficial nodes:
- Horizontal group: along the inguinal ligament, between the lower abdomen and thigh
- Vertical group: along the upper great saphenous vein on the upper inner side of the thigh
- Deep (femoral) nodes: along the femoral artery
Drainage:
- Superficial horizontal group: the abdominal wall below the belly button, retroperitoneal space (around the kidneys), penis and scrotum skin, anal canal, vulva and lower third of the vagina, perineum, buttocks and lower back [1,3,5]
- Superficial vertical group: penis, scrotum, thighs and–via the popliteal nodes–the lower legs
- Deep (femoral) nodes: the legs, penis, clitoris [18]
Efferent vessels lead to the external iliac nodes in the pelvis [18].
Legs
Popliteal Nodes
Location: at the back of the knee, in the popliteal fossa [18]
Drainage: the foot, lower leg and knee [18]
Efferent vessels lead to the deep and superficial inguinal nodes [18].
- References
- Bazemore AW et al, 2002, Lymphadenopathy and malignancy American Family Physician
- Kanwar VS, Lymphadenopathy, overview Emedicine
- Kanwar VS, Lymphadenopathy, clinical presentation Emedicine
- Ferrer R, 1998, Lymphadenopathy: Differential Diagnosis and Evaluation American Family Physician
- Swollen lymph nodes Cleveland Clinic
- Lymphadenopathy of the Head and Neck Family Practice Notebook
- Werner JA et al, 2004, Metastases in Head and Neck Cancer. pp.11-13
- Grey H, Anatomy of the human body, The Lymphatics of the Head, Face, and Neck Bartleby
- Head and neck exam University of California, San Diego
- Grey H, Anatomy of the human body, The Lymphatics of the Upper Extremity Bartleby
- Laronga C et al, 2016, Patient education: Breast cancer guide to diagnosis and treatment (Beyond the Basics) UpToDate
- Grey H, Anatomy of the human body, The Lymphatics of the Abdomen and Pelvis Bartleby
- Grey H, Anatomy of the human body, The Lymphatics of the Thorax Bartleby
- Gow KW, Pediatric lymph nodes disorders, overview Emedicine
- Willard-Mack CL, 2006, Normal Structure, Function, and Histology of Lymph Nodes Toxicologic Pathology
- Kumar M, 2013, Lymphatic drainage of head & neck SlideShare
- Jaffar AA, 2012, Anatomy of the lymphatic system SlideShare
- Lymph nodes of the pelvis and lower limb Kenhub
- Lymph nodes of the head, neck and arm Kenhub
- Richter E et al, 2004, Normal Lymph Node Topography, CT Atlas
- Jugulodigastric lymph node MediLexicon
- Hay JB et al, 1977, THE FLOW OF BLOOD TO LYMPH NODES AND ITS RELATION TO LYMPHOCYTE TRAFFIC AND THE IMMUNE RESPONSE PubMed Central Europe
- Anatomy tables – lymphatics of the abdomen University of Michigan, Medical School
- Mizutani M et al, 2005, Anatomy and histology of Virchow’s node PubMed
- Supraclavicular lymph nodes General Practice Notebook
- Gosselin BJ, Neck, cervical metastases, detection Emedicine
- Cervical lymph nodes, anatomy & examination The Lung Center